1. Field
The present disclosure relates to occlusion and drug delivery devices, systems, and methods. Such devices and methods can be useful for tissue ablation, tissue and/or vascular drug delivery, and temporary and/or permanent vessel occlusion.
2. Discussion of the Related Art
The systemic administration of therapeutic agents treats the body as a whole even though the disease to be treated may be localized. In some cases of localized condition or disease, systemic administration may not be desirable because the drug agents may have deleterious or unwanted effects on parts of the body which are not to be treated or because treatment of the diseased part of the body requires a high concentration of drug agent that may not be achievable by systemic administration. It is therefore often desirable to administer therapeutic agents to only localized sites within the body. Common examples of where this is needed include cases of localized disease (e.g., heart disease and saphenous vein incompetence) and occlusions or lesions in body lumens. Several devices and methods for localized drug delivery are known.
Typically, with these types of treatments, an elongate member, such as a catheter, traverses the vasculature with a drug containing device mounted on the end. Once the target area is reached, the drug containing device delivers the drug. While the specifics of the drug containing device and the mode of delivery can vary, the problems encountered with these devices are usually the same.
Some of the problems encountered include dilution of the therapeutic agent with body fluids, migration away from the treatment area, and adverse effects caused by the migration. For example, in a method of treating an incompetent saphenous vein, chemical ablation involves treating the target vessel with a sclerosant that actually injures the contacted tissue. As expected by its effect, sclerosants are highly toxic and thus migration should be avoided to the extent possible to minimize unwanted side effects. Sclerosant migration through the vasculature has been linked with deep venous thrombosis, pulmonary embolism, ulceration and neurological events such as migraines, transient ischemic attacks and cerebrovascular accidents. In addition, sclerosants can have a high price per unit, so minimizing the amount utilized to effect treatment is also desirable.
Complicating the ability of designing drug delivery devices and modes of treatment that minimize the issues discussed above is the tortuosity of the vessel, both traversing a tortuous, narrow vessel and treating a tortuous section of a vessel. For example, tortuosity often occurs in the Greater Saphenous Vein (GSV) and can pose difficulty. In the case of the GSV, the treatment site may be, for example, 30-40 cm or more of a tortuous vein.
As can be appreciated by the example of saphenous vein sclerotherapy, improvements in vascular drug delivery that improve delivery rates or efficacy, minimize dilution, and/or minimize migration are desired.